EP2870191B1 - Catalysts for the production of cast polyamide, method for producing and using same - Google Patents

Description

The present invention relates to novel catalysts for the production of cast polyamide, processes for their preparation and their use.

Cast polyamides are particularly high molecular weight polyamides. In the production of cast polyamides, a lactam is poured into a mold together with at least one catalyst and at least one activator and then anionically polymerized in this form. The starting compounds present in the form polymerize generally under the action of heat. The result is a homogeneous material, which exceeds extruded polyamides in terms of crystallinity.

Cast polyamides are suitable as thermoplastic materials for the production of complex components. In contrast to many other thermoplastics, they do not need to be melted, but are formed by anionic polymerization of the lactam in a mold at 120 ° to 150 ° C. in just a few minutes. In this case, all known casting methods, such as casting, injection molding, rotary and centrifugal casting, can be applied. The final product obtained in each case molded parts from a high molecular weight, crystalline polyamide, which is characterized by a low weight, high mechanical strength, very good sliding properties and excellent chemical resistance and - since the molds are not filled under pressure - has only low internal stresses , Cast polyamides can be sawing, drilling, milling, grinding, welding and printing or painting; In addition to complex molds are made of this polymer, for example, rolls for passenger lifts and semi-finished products, such as tubes, rods and plates for mechanical engineering and the automotive industry.

The production of cast polyamide parts, starting from low-viscosity lactam melts and a catalyst and an activator, by the so-called activated anionic polymerization, is known per se. For this purpose, usually two mixtures of catalyst and lactam or activator and lactam in the form of a liquid melt are mixed together and then polymerized in the mold, see EP-A-2447302 , Out US Pat. No. 3,663,670 For example, a process for the polymerization of lactams is known, after which lactam and sodium hydride are reacted in the presence of potassium stearate and then this mixture is reacted with further lactam. A disadvantage of the current catalysts for cast polyamides, however, is the too high and not constant reactivity. This leads to poorer product properties, such. B. low crystallinity, and makes the procedure especially for large castings uneconomical.

The object of the present invention was therefore to provide new compositions which are suitable as catalysts in the preparation of cast polyamides, and which do not have the disadvantages of the prior art.

Surprisingly, it has now been found that the compositions according to the invention have this property profile.

1. a) mindestens ein Lactamat und
2. b) mindestens ein Salz einer mit Heteroatomen substituierten organischen Säure und/oder Ester einer mit Heteroatomen substituierten organischen Säure und gegebenenfalls
3. c) mindestens ein Lactam.

The subject of the present invention are thus compositions containing

1. a) at least one lactamate and
2. b) at least one salt of a heteroatom-substituted organic acid and / or ester of a heteroatom-substituted organic acid and optionally
3. c) at least one lactam.

In a preferred embodiment of the invention, lactamates a) are at least one compound selected from the group of alkali aluminum dilactamates, alkali metal and / or alkaline earth metal lactamates.

Preferred as lactamate in the context of the invention are alkali metal and / or alkaline earth metal lactamates, preferably sodium, potassium and / or magnesium, individually or in a mixture.

The aforementioned lactamates are commercially available and are available, for example, from Rhein Chemie Rheinau GmbH.

In a preferred embodiment of the invention, the ester b) is C ₁ -C ₆ -alkyl ester, preferably methyl, and / or ethyl ester. The heteroatom-substituted organic acid preferably has 1-12 carbon atoms, preferably 4-6 carbon atoms.

In a preferred embodiment of the invention, the salt of an organic acid substituted by heteroatoms, preferably amino groups, b) has 1 to 12 carbon atoms, more preferably 4 to 6 carbon atoms.

In a particularly preferred embodiment of the invention, the heteroatoms are nitrogen, sulfur, phosphorus, preferably nitrogen, particularly preferably amino groups, and / or halides, preferably chlorine and / or bromine.

The salt of a heteroatom-substituted organic acid and / or ester of a heteroatom-substituted organic acid b) is particularly preferably aminocapronates and / or aminolaurates, preferably alkali metal and / or alkaline earth metal aminocapronates and / or laurates, particularly preferably sodium , Potassium and / or magnesium aminocapronate.

wobei R* eine Alkylengruppe mit 3 bis 13 Kohlenstoffatomen darstellt.In a preferred embodiment of the invention, the lactam c) is a compound of the general formula

wherein R * represents an alkylene group having 3 to 13 carbon atoms.

Preference is given to capro-lactam and / or lauryl lactam. These are commercially available, e.g. at the Lanxess Germany GmbH.

The composition according to the invention preferably has components a) and b) in a ratio of 3: 1 to 50: 1, preferably 5: 1 to 40: 1, particularly preferably 9: 1.

The content of lactam c), based on constituents a) and b), is preferably 0-99% by weight, particularly preferably 50-85% by weight.

Another object of the invention is a process for the preparation of the composition according to the invention in which the lactamate a) by reacting at least one lactam, which lactam c), but may also be different, with alkali or alkaline earth alcoholates in the presence of at least one salt of a heteroatom-substituted organic acid and / or ester of a heteroatom-substituted organic acid b) is prepared by subsequent or simultaneous removal of the resulting alcohol by distillation and then optionally further lactam c) is added.

In a preferred embodiment of the process according to the invention, the lactamate a) is converted by reaction of lactam, preferably caprolactam, which corresponds to lactam c), but may also be different therefrom, with Na-methoxide in the presence of Na-aminocapronate and / or Na-Aminolaurate b) produced by subsequent or simultaneous removal of the resulting alcohol by distillation and then optionally further lactam c) was added.

In a further preferred embodiment of the process according to the invention, the lactamate a) is reacted by reacting at least one caprolactam in excess, which corresponds to lactam c), with Na-methoxide in the presence of Na-aminocaproate and / or Na-aminolaurate b) in subsequent or simultaneous Removal of the resulting alcohol produced by distillation.

The aforementioned reactions, i. the preparation of the lactamate and the distillation are preferably carried out at temperatures of 80 ° - 130 ° C.

The process according to the invention can be carried out both as a batch process and in a continuous process. In this case, the salts of a heteroatom-substituted organic acid and / or esters of heteroatom-substituted organic acids before, during and / or after the preparation of the lactamate a) can be added.

Likewise preferred is the process variant in which the salts of a heteroatom-substituted organic acid and / or esters of heteroatom-substituted organic acids are formed "in situ". In a preferred embodiment of the invention, the in situ preparation of the salts of a heteroatom-substituted organic acid and / or esters of heteroatom-substituted organic acids b) by addition of acids, water and / or alkali and / or alkaline earth metal hydroxides to a) and if necessary c). Particularly preferred is the addition of stoichiometrically required amounts of water to adjust the desired salt concentrations.

In a further embodiment of the invention, the lactamate a) is melted at temperatures of 80-120 ° C., optionally together with lactam c), and with at least one salt of a heteroatom-substituted organic acid and / or ester of the heteroatom-substituted organic acid b), preferably with stirring.

For stirring, commercially available stirring units, such as preferably stirred tanks or mixers, can be used.

Another object of the invention are compositions obtainable by the aforementioned inventive method. With respect to this subject matter of the invention, reference is made to the above statements, including all preferred embodiments.

Likewise subject of the invention are cast polyamides, obtainable by the polymerization of lactams with at least one inventive composition of a) and b) and optionally c) at temperatures of 80-180 ° C, preferably of 120 and 160 ° C, in the presence of activators and optionally further additives and auxiliaries.

The preparation is preferably carried out according to the molding process familiar to the person skilled in the art, such as, preferably, injection molding, continuous casting and / or rotational casting.

The polymerization of lactams is preferably carried out by adding the inventive composition in the melted at temperatures of 80 - 120 ° C lactam and subsequent addition of a Lactamschmelze with at least one activator and other additives and excipients.

The polymerization for producing the cast polyamides is preferably carried out directly in the casting mold.

The polymerization is preferably carried out under exclusion of atmospheric moisture z. B. in a vacuum or in an inert atmosphere.

As activators for the purposes of the invention, isocyanates, isocyanurates, biurets, allophanates, uretdiones and / or carbodiimides may be used as a single compound or in the form of a mixture. Also usable in the context of the invention are activators that are blocked, z. B. with lactams, particularly preferably caprolactam, with phenols, oximes and / or epoxides as well as solvent-containing activators. Suitable solvents are: N-alkylpyrrolidones, preferably, N-methylpyrrolidone and N-ethylpyrrolidone, polyglycols, preferably polyglycol DME 200, dipropylene glycol DME or tetraethylene glycol DME.

Isocyanates according to the invention are preferably diisocyanates, more preferably 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene-1,6-diisocyanate, cyclohexane 1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1 , 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2,6- Diisopropylphenylene isocyanate and mixtures thereof. Particularly preferred is hexamethylene-1,6-diisocyanate. The abovementioned compounds are commercially available and are obtainable, for example, from Bayer MaterialScience AG.

• mit R¹, R² und R³ jeweils unabhängig voneinander -(CH₂)_m-N=C=O oder-(CH₂)_q-[(C₆H₃)(Me/Et)₃(N=C=O)] sind, und m = 1 - 12, q = 0 - 6 und Me für Methyl und Et für Ethyl steht, wobei
• R¹, R² und R³ vorzugsweise gleich sind.

Isocyanurates in the context of the invention are preferably compounds of the formula (I)

• with R ¹ , R ² and R ³ each independently of one another - (CH ₂ ) _m -N = C = O or - (CH ₂ ) _q - [(C ₆ H ₃ ) (Me / Et) ₃ (N = C = O)], and m = 1-12, q = 0-6 and Me is methyl and Et is ethyl, wherein
• R ¹ , R ² and R ^{3 are} preferably the same.

und der Formel (III)

bevorzugt.The following compounds of the formula (II)

and the formula (III)

prefers.

The abovementioned compounds are commercially available and are obtainable, for example, from Bayer MaterialScience AG.

• mit R^IV, R^V und R^VI jeweils unabhängig voneinander -(CH₂)_p-N=C=O, mit p = 1 - 12, wobei
• R^IV , R^V und R^VI vorzugsweise gleich sind.

Biurets within the meaning of the invention are preferably compounds of the formula (IV)

• with R ^IV , R ^V and R ^VI each independently of one another - (CH ₂ ) _{p -N} = C = O, with p = 1-12, where
• R ^IV , R ^V and R ^{VI are} preferably the same.

In a particularly preferred embodiment of the invention, the biuret is a compound of the formula (V), ie a biuret of the formula (IV) where R ^IV , R ^V and R ^VI = - (CH ₂ ) _p -N = C = O and p = 6

The abovementioned compounds are commercially available and are obtainable, for example, from Bayer MaterialScience AG.

Uretdiones in the context of the invention are reaction products of at least two isocyanates with the formation of dioxodiazetidine bonds:

The preparation is known per se to the person skilled in the art. The compounds may, for example, according to the in EP 1 422 223 A1 be prepared described methods.

The uretdione may be a dimer, trimer, oligomer or polymer.

Suitable examples of uretdiones are known per se to the person skilled in the art. Preference is given to uretdiones which are obtained starting from an aliphatic or aromatic isocyanate. The aromatic isocyanates have as R preferably 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms. Corresponding aromatic monomeric isocyanates may, for example, be selected from the group consisting of 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 1,5-naphthylene diisocyanate, 4,4'-methylene diphenyl diisocyanate, 1,3-bis (3 isocyanato-4-methylphenyl) -2,4-dioxodiazetidine, N, N'-bis (4-methyl-3-isocyanatophenyl) urea and tetramethylxylylene diisocyanate. Of these aromatic isocyanates, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene and 4,4'-methylene-bis (phenyl diisocyanate) are preferable. Particularly preferred are 2,6-diisocyanatotoluene and 4,4'-methylene-bis (phenyl diisocyanate).

The aliphatic isocyanates have as R preferably 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms. Corresponding aliphatic monomeric isocyanates may for example be selected from the group consisting of isophorone diisocyanate, 1,4-cyclohexyl diisocyanate, 1,1-methylene-bis (4-isocyanatocyclohexane), 1,2-bis (4-isocyanatononyl) -3- heptyl-4-pentylcyclohexane and hexamethylene-1,6-diisocyanate. Here, the use of isophorone diisocyanate and hexamethylene-1,6-diisocyanate is preferred.

The abovementioned compounds are commercially available and are obtainable, for example, from Rhein Chemie Rheinau GmbH or Bayer MaterialScience AG.

wobei R' und R" unabhängig voneinander ein Alkylrest mit 1 bis 20 Kohlenstoffatomen oder ein Arylrest mit 6 bis 20 Kohlenstoffatomen ist,
und R'" die Bedeutung eines Alkylrestes mit 1 bis 20 Kohlenstoffatomen hatAllophanates within the meaning of the invention are preferably compounds of the formula (VI)

where R 'and R "independently of one another are an alkyl radical having 1 to 20 carbon atoms or an aryl radical having 6 to 20 carbon atoms,
and R '"has the meaning of an alkyl radical having 1 to 20 carbon atoms

These compounds are generally obtained by reacting any urethane and / or urea group-containing starting compounds containing units of the general formula (R "OOC-NHR '), with monoisocyanates of the general formula R"' - NCO or with diisocyanates general formula OCN-A-NCO accessible, wherein R '"or A is preferably an alkyl radical having 1 to 20 carbon atoms or an aryl radical having 6 to 20 carbon atoms and R' and R" are independently alkyl radicals having 1 to 20 carbon atoms or aryl radicals with 6 to 20 carbon atoms.

Suitable monoisocyanates are any aromatic, aliphatic and cycloaliphatic monoisocyanates containing up to 20 carbon atoms, such as methyl isocyanate, isopropyl isocyanate, n-butyl isocyanate, n-hexyl isocyanate, cyclohexyl isocyanate, stearyl isocyanate, the optionally halogenated phenyl isocyanates, 1-naphthyl isocyanate, which may be chlorinated or fluorinated. , o-, and p-tooleyl isocyanates, p-isopropylphenyl isocyanate, 2,6-diisopropylphenyl isocyanate and p-toluenesulfonyl diisocyanate.

Suitable diisocyanates are any aromatic, aliphatic and cycloaliphatic diisocyanates having 6 to 40 carbon atoms, preferably 6 to 15 carbon atoms, more preferably isophorone diisocyanate, 1,4-cyclohexyl diisocyanate, 1,1-methylene-bis- (isocyanatohexane), 1,2- Bis (4-isocyanatononyl) -3-heptyl-4-pentylcyclohexane, hexamethylene-1,6-diisocyanate, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 1,5-naphthylene diisocyanate, 4,4'-methylene diphenyl diisocyanate , 1,3-bis (3-isocyanto-4-methylphenyl) -2,4-dioxodiazetidine, N, N'-bis (4-methyl-3-isocyanatophenyl) urea and tetramethylxylylene diisocyanate. Preferred of these is hexamethylene-1,6-diisocyanate.

wobei R⁴ und R⁶ innerhalb des Moleküls gleich oder verschieden sein können und C₁-C₆-Alkyl, vorzugsweise -(CH₂)₆- bedeuten, und R⁵ C₁-C₆-Alkyl entspricht.The allophanates which are particularly preferred in the context of the present invention are compounds of the formula (VII)

wherein R ⁴ and R ⁶ may be the same or different within the molecule and C ₁ -C ₆ alkyl, preferably - (CH ₂ ) ₆ -, and R ^{5 is} C ₁ -C ₆ alkyl.

Corresponding allophanates and their preparation are for example in the EP 0 000 194A whose disclosure in the present invention is incorporated by reference. The abovementioned compounds are commercially available and are obtainable, for example, from Bayer MaterialScience AG.

• m einer ganzen Zahl von 1 bis 500 entspricht,
• R¹² für C₁-C₁₈-Alkylen, C₅-C₁₈-Cycloalkylen-, Arylen und/oder C₇-C₁₈- Aralkylen steht
• R¹¹ für R¹²-NCO, R¹²-NHCONHR⁹, R¹²-NHCONR⁹R⁷ oder R¹²-NHCOOR⁸ steht und
• R¹³ steht -NCO, -NHCONHR⁹, -NHCONR⁹R⁷ oder -NHCOOR⁸ steht,
• wobei in R¹¹ unabhängig voneinander R⁹ und R⁷ gleich oder verschieden sind und einen C₁-C₆-Alkyl-, C₆-C₁₀-Cycloalkyl- oder C₇-C₁₈-Aralkylrest darstellen und R⁸ eine der Bedeutungen von R¹¹ hat oder einen Polyester- oder Polyamidrest oder -(CH₂)_h-O-[(CH₂)_k-O]_g-R¹⁰ entspricht,
• mit h = 1-3, k= 1-3, g = 0-12, wobei
• R¹⁰ die Bedeutung von H oder C₁-C₄-Alkyl hat.

Carbodiimides in the context of the invention are preferably compounds of the formula (VIII)

R ¹¹ - (- N = C = NR ¹² ) _m -R ¹³ (VIII),

in the

• m is an integer from 1 to 500,
• R ^{12 is} C ₁ -C ₁₈ alkylene, C ₅ -C ₁₈ cycloalkylene, arylene and / or C ₇ -C ₁₈ aralkylene
• R ^{11 is} R ¹² -NCO, R ^{12 is} -NHCONHR ⁹ , R ^{12 is} -NHCONR ⁹ R ⁷ or R ^{12 is} -NHCOOR ⁸ and
• R ¹³ is -NCO, -NHCONHR ⁹ , -NHCONR ⁹ R ⁷ or -NHCOOR ⁸ ,
• where in R ¹¹ independently of one another R ⁹ and R ^{7 are} identical or different and represent a C ₁ -C ₆ -alkyl, C ₆ -C ₁₀ -cycloalkyl or C ₇ -C ₁₈ -aralkyl radical and R ^{8 has} one of the meanings of R ¹¹ has or is a polyester or polyamide radical or - (CH ₂ ) _h -O - [(CH ₂ ) _k -O] _g -R ¹⁰ ,
• with h = 1-3, k = 1-3, g = 0-12, where
• R ^{10 has} the meaning of H or C ₁ -C ₄ alkyl.

Also suitable are mixtures of carbodiimides of the formula (VIII), including the corresponding oligomers and / or polymers, with polymeric carbodiimides being preferred.

The compounds of the formula (VIII) are commercially available, for example from Rhein Chemie Rheinau GmbH, or can be prepared by the processes familiar to the person skilled in the art, as described, for example, in US Pat DE-A-11 30 594 or US-A 2,840,589 or by the condensation of diisocyanates with elimination of carbon dioxide at elevated temperatures, for example at 40 ° C to 200 ° C, in the presence of catalysts. As catalysts preferably strong bases or phosphorus compounds have proven. Preference is given to using phospholene oxides, phospholidines or phospholine oxides and the corresponding sulfides. Further, as catalysts, tertiary amines, basic metal compounds, carboxylic acid metal salts and non-basic organometallic compounds can be used.

The abovementioned compounds are commercially available and are obtainable, for example, from Rhein Chemie Rheinau GmbH.

Blocked activators, preferably with lactams, particularly preferably caprolactam, or activators blocked with phenols, oximes and / or epoxides can be prepared, for example, by reacting at least one compound of the formulas (I) to (VIII) with at least one lactam, Caprolactam, phenol, oxime and / or epoxide at temperatures of 80 to 100 ° C according to the methods known in the art.

For the preparation of the cast polyamides, the following proportions are preferably used in one embodiment of the invention, based on lactam:
0.1 to 3 wt.%, Preferably 0.2 to 1.5 wt.% Of the inventive composition and 0.1 to 2 wt.%, Preferably 0.5 to 1 wt.% Of activator.

In a preferred embodiment of the invention, the cast polyamide is obtainable by the polymerization of lactam, preferably caprolactam
0.1 to 3 wt.% Of the inventive composition containing sodium lactamate a) as preferably 18-20 wt.% Caprolactam solution with 0.1 to 5 wt.%, Preferably, 0.5 to 4 wt.%, Particularly preferably 1.5-2.5% by weight of Na-aminocapronate and
0.1 to 2% by weight of at least one representative selected from the group of hexamethylene-1,6-diisocyanate, caprolactam-blocked hexamethylene-1,6-diisocyanate, biuret of the formula (V) with p = 6 and / or a uretdione based on 2,4-diisocyanatotoluene as activator.

In a further preferred embodiment of the invention, the mixture for the production of cast polyamides additionally contains at least one further additive and adjuvant, selected from fillers and / or reinforcing materials, polymers and / or further additives.

Fillers and / or reinforcing agents in the context of the invention are organic or inorganic fillers and / or reinforcing materials. Preference is given to inorganic fillers, in particular kaolin, chalk, wollastonite, talc, calcium carbonate, silicates, titanium dioxide, zinc oxide, graphite, graphenes, glass particles (eg glass spheres), nanoscale fillers (such as carbon nanotubes carbonanotubes), carbon black, phyllosilicates, nanoscale phyllosilicates , nanoscale alumina (Al ₂ O ₃ ), nanoscale titania (TiO ₂ ), and / or nanoscale silica (SiO ₂ ).

Further preferred is the use of fibers as filling and / or reinforcing material. The fillers and / or reinforcing materials are usually selected from the group comprising minerals in customary for thermoplastic applications grain size, in particular kaolin, chalk, wollastonite or talc, carbon or glass fibers, preferably ground glass fibers, particularly preferably glass and carbon fibers.

Particular preference is given to using one or more fibrous materials selected from known inorganic reinforcing fibers, in particular boron fibers, glass fibers, carbon fibers, silica fibers, ceramic fibers and basalt fibers; organic reinforcing fibers, especially aramid fibers, polyester fibers, nylon fibers, polyethylene fibers; and natural fibers, especially wood fibers, flax fibers, hemp fibers and sisal fibers. Particularly preferred is the use of glass fibers, in particular chopped glass fibers, carbon fibers, aramid fibers, boron fibers, metal fibers and / or potassium titanate fibers.

In particular, it is also possible to use mixtures of the stated fillers and / or reinforcing materials. Glass fibers and / or glass particles, in particular glass beads, are particularly preferably selected as fillers and / or reinforcing materials.

The amount of fillers and / or reinforcing substances to be used is preferably from 30 to 90% by weight, in particular from 30 to 80% by weight, preferably from 30 to 50% by weight, more preferably from 50 to 90% by weight.

Polymers in the context of the invention are: polystyrene, styrene copolymers, in particular styrene-acrylonitrile copolymers (SAN), acrylonitrile-butadiene-styrene copolymers (ABS) or styrene-butadiene copolymers (SB), polyphenylene oxide ethers, polyolefins, in particular polyethylene (HTPE ( high-temperature polyethylene), LTPE (low-temperature polyethylene), polypropylene or polybutene-1, polytetrafluoroethylene, polyesters, in particular polyethylene terephthalate (PET), polyamides, polyethers, in particular polyethylene glycol (PEG), polypropylene glycol or polyethersulfones (PESU or PES) Polymers made from vinyl groups contain monomers, in particular polyvinyl chloride, polyvinylidene chlorides, polystyrene, impact-modified polystyrene, polyvinylcarbazole, polyvinyl acetate or polyvinyl alcohol, polyisobutylenes polybutadiene and / or polysulfones Furthermore, the use of copolymers as polymer consisting of the monomer units of the above-mentioned Polymers exist.

In a further embodiment of the invention, the polymer to be used may contain groups which are suitable for forming block and / or graft copolymers with the polymer formed from the monomers. Examples of such groups are epoxy, amine, carboxyl anhydride, oxazoline, carbodiimide, urethane, isocyanate and lactam groups. Polymers with carbodiimide groups are used when no carbodiimide is used as activator.

Optionally contained polymer is preferably contained in an amount of 0 to 40 wt .-%, preferably from 0 to 20 wt .-%, particularly preferably in an amount of 0 to 10 wt .-%.

In a preferred embodiment, the composition according to the invention contains further additives. The additives are preferably used in an amount of from 0 to 5% by weight, particularly preferably from 0 to 4% by weight, very particularly preferably from 0 to 3.5% by weight. Stabilizers, in particular copper salts, dyes, antistatic agents, fillers, stabilizers, surface improvers, siccatives, mold release agents, release agents, antioxidants, light stabilizers, PVC stabilizers, lubricants, polyols, flame retardants, blowing agents, impact modifiers and / or nucleating agents may preferably be added as additives ,

Particularly suitable impact modifiers are polydiene polymers, preferably polybutadiene, polyisoprene, containing anhydride and / or epoxy groups. The polydiene polymer has a glass transition temperature below 0 ° C, preferably below -10 ° C, more preferably below -20 ° C. The polydiene polymer can be based on a polydiene copolymer with polyacrylates, polyethylene acrylates and / or polysiloxanes and prepared by the usual methods, preferably by emulsion polymerization, suspension polymerization, solution polymerization, gas phase polymerization.

In a further preferred embodiment of the invention is used as an additive polyol to improve the impact resistance. These are e.g. available from Rhein Chemie Rheinau GmbH under the name Addonyl® 8073. Also usable are polyoltriamines suitable for improving the low-temperature impact strength. A suitable product is Addonyl® 8112. Preferably, the polyols are used in the concentration range 1-20 wt .-%.

The optional addition of fillers and / or reinforcing materials and other additives can be carried out before or together with the addition of catalyst and / or activator.

In a further embodiment of the present invention, the polymerization for the production of cast polyamides may be carried out by a suitable molding process, preferably injection molding, casting, rotational molding.

Injection molding, stand casting, rotational molding process are familiar to those skilled in the process.

The scope of the invention covers all of the above-mentioned general or preferred radical definitions, indices, parameters and explanations with one another, ie also between the respective ranges and preferred ranges in any desired combination.

Another object of the present invention is the use of the composition of the invention as a catalyst for the production of cast polyamide.

In addition, the use of the composition according to the invention for the production of rolls, preferably for passenger lifts and semi-finished products, preferably containers, gears, tubes, rods and plates for mechanical engineering and the automotive industry is a further subject of the invention.

The following examples serve to illustrate the invention without being limiting.

EXAMPLES reagents:

Caprolactam dry (EP> 69 ° C) from the company Lanxess Germany GmbH
Activator, a hexamethylene-1,6-diisocyanate (HDI) biuret, 70% in N-ethylpyrrolidone, commercially available from Rhein Chemie Rheinau GmbH,
Inventive composition as catalyst (A) with about 18% sodium caprolactamate and 2.0% sodium aminocapronate in caprolactam.

Composition of the prior art as catalyst (B) with about 18% sodium caprolactamate in caprolactam, comparison.

Equipment:

• 2 Dreihalskolben (500 ml) im Ölbad beheizt
• 2 KPG-Rührer mit Hülse
• 2 Gaskappen je 1 mit und 1 ohne Hahn
• 1 Vakuumpumpe mit Kühlfalle und Manometer.

The apparatus used for melt processing consisted of:

• 2 three-necked flasks (500 ml) heated in an oil bath
• 2 KPG stirrer with sleeve
• 2 gas caps each with 1 and 1 without tap
• 1 vacuum pump with cold trap and pressure gauge.

• Temperaturmessgerät Testo 175-T3 mit IR-Serial Interface
• Thermodraht zum Verbleib in der ausgehärteten Probe
• Becherglas 600 ml (hohe Form) und einer
• Beheizung für das Becherglas (Metallblock, Ölbad).

The temperature measuring apparatus used consisted of:

• Temperature measuring device Testo 175-T3 with IR-Serial Interface
• Thermal wire to remain in the cured sample
• Beaker 600 ml (high form) and one
• Heating for the beaker (metal block, oil bath).

Carrying out and measuring the pot life:

Flask A was charged with 196.8 g of caprolactam and 3.2 g of activator, flask B1 / 2 with 192 g of caprolactam and 8 g of catalyst (A) and (B), respectively.

The melts from flask A and flask B1 / 2 were conditioned at 110-130 ° C (± 2 ° C) in an oil bath under vacuum (<15 mbar) for 20 minutes.

After venting with nitrogen, components from flask A and flask B were combined in a three-necked flask, stirred briefly and transferred to the 600 ml beaker.

The mold temperature (beaker) was 160 ° C. The polymerization time was generally 10 to 20 minutes.

The turbidity tests were carried out in a drying oven at 85 ° C. after a period of 3 hours. The assessment was done visually.

The evaluation of the quality of the cast polyamides in terms of crystallinity and homogeneity was carried out on the basis of SEM images (scanning electron microscope). Catalyst in flask B1 / 2 pot life turbidity test Crystallinity / homogeneity (S) (85 ° C, 3 h) cast nylon Catalyst A (erf.) 380 bright high Catalyst B (V) 270 very cloudy low Comparative Example = Comp., Inventive = Comp.

The blends of the prior art have i.d.R. Pot lives of <300s, resulting in inhomogeneities and a low crystallinity of the cast polyamide. In addition, the melts containing the catalyst polymerize already in the template and thus clog the filter upstream of the mold.

The examples show that the catalyst according to the invention has pot lives of well over 300s. Moreover, the compositions according to the invention do not tarnish.

As a result, it is also possible to produce large-volume high-quality cast polyamide parts. Furthermore, the quality of the cast polyamides thus produced can be significantly improved with respect to crystallinity or homogeneity.

Claims (14)

1. Composition comprising

   a) at least one lactamate and

   b) at least one salt of an organic acid substituted by heteroatoms and/or ester of an organic acid substituted by heteroatoms, and optionally

   c) a lactam or a mixture of two or more lactams.
2. Composition according to Claim 1, characterized in that the lactamate is at least one compound selected from the group of the alkali metal aluminodilactamates and alkali metal and/or alkaline earth metal lactamates.
3. Composition according to one or more of Claims 1 and 2, characterized in that the ester b) comprises alkyl esters, preferably methyl and/or ethyl esters.
4. Composition according to one or more of Claims 1 and 2, characterized in that the salt of the organic acid b) substituted by heteroatoms, preferably by amino groups, has 1 to 12 carbon atoms, preferably 4 to 6 carbon atoms.
5. Composition according to one or more of Claims 1 to 4, characterized in that the heteroatoms are nitrogen, sulfur, phosphorus, preferably nitrogen, and/or halides, preferably chlorine and/or bromine.
6. Composition according to Claim 5, characterized in that the salt of an organic acid substituted by heteroatoms and/or ester of an organic acid b) substituted by heteroatoms comprises aminocapronates and/or aminolaurates, preferably alkali metal and/or alkaline earth metal aminocapronates and/or -laurates, more preferably sodium aminocapronate, potassium aminocapronate and/or magnesium aminocapronate.
7. Composition according to one or more of Claims 1 to 6, characterized in that the lactam corresponds to the general formula

   

   where R* is an alkylene group having 3 to 13 carbon atoms.
8. Composition according to one or more of Claims 1 to 7, characterized in that constituents a) and b) are present in a ratio of 3:1 to 50:1, preferably 5:1 to 40:1, more preferably 9:1, and the proportion of lactam c), based on constituents a) and b), is preferably 0-99% by weight, more preferably 50-85% by weight.
9. Process for preparing composition according to one or more of Claims 1 to 8, characterized in that the lactamate a) is prepared by reaction of at least one lactam which corresponds to or else may be different than lactam c) with alkali metal or alkaline earth metal alkoxides in the presence of at least one salt of an organic acid substituted by heteroatoms and/or ester of an organic acid b) substituted by heteroatoms with subsequent or simultaneous removal of the alcohol formed by distillation, and then further lactam c) is optionally added.
10. Process for preparing composition according to Claim 9, characterized in that the salts of an organic acid substituted by heteroatoms and/or esters of the organic acids substituted by heteroatoms are prepared in situ by addition of acids, water and/or alkali metal and/or alkaline earth metal hydroxides to a) and optionally c).
11. Cast polyamides obtainable by the polymerization of lactams with at least one composition of Claims 1 to 8 at temperatures of 80-180°C, optionally in the presence of activators and/or further additives and assistants.
12. Process for producing cast polyamides obtainable by the polymerization of lactams with at least one composition of Claims 1 to 8 at temperatures of 80-120°C, preferably 120-160°C, in the presence of activators and optionally further additives and assistants.
13. Use of the composition according to one or more of Claims 1 to 8 as a catalyst for the production of cast polyamide.
14. Use of the composition according to one or more of Claims 1 to 8 for production of rollers, preferably for passenger elevators and semifinished products, for vessels, gears, tubes, bars and sheets for mechanical engineering and the automobile industry.